1. Field
The technology described herein relates to apparatus and methods for reducing noise in oscillating signals.
2. Related Art
Today's high speed communication systems and RADAR systems require signal sources with low phase noise, which themselves need low phase noise reference signals. Today's low noise reference signal generators are usually based on Quartz crystals, surface acoustic wave (SAW), microelectromechanical systems (MEMS), nanoelectromechanical systems (NEMS), bulk acoustic wave (BAW), or FBAR resonators, and the minimum phase noise of the resulting reference signal that can be achieved is constrained by the quality factor of the resonator, the power handling capabilities of the resonator, and by the noise generated in the oscillator circuitry of the reference signal generator coupled to the resonator (i.e., noise due to the currents in the oscillator circuitry).